Energetic constraints to chemo-photometric evolution of spiral galaxies

The problem of chemo-photometric evolution of late-type galaxies is dealt with relying on prime physical arguments of energetic self-consistency between chemical enhancement of galaxy mass, through nuclear processing inside stars, and luminosity evolution of the system. Chemical enhancement is assessed in terms of the so-called "yield metallicity", that is the metal abundance of processed mass inside stars, as constrained by the galaxy photometric history.